libchealpix-dev binary package in Ubuntu Focal amd64

 HEALPix is an acronym for Hierarchical Equal Area isoLatitude Pixelization
 of a sphere. As suggested in the name, this pixelization produces a
 subdivision of a spherical surface in which each pixel covers the same
 surface area as every other pixel. It is commonly used to store all-sky
 astronomical images, most famously maps of the cosmic microwave background.
 .
 This package provides the static library and headers for the C language
 implementation of HEALPix. The C library provides basic input/output of
 HEALPix maps as well as basic spatial operations like conversion between
 spherical coordinates and HEALPix pixels.

Source package